1. Field of the Invention
The structure of this invention resides in the area of hand-held umbrellas and more particularly relates to an umbrella having aerodynamic features.
2. Description of the Prior Art
Umbrellas are usually concave, inverted, fabric-covered canopy structures supported by a plurality of struts and ribs mounted on a central mast. The designs of typical prior art umbrellas have been primarily limited to rounded, curved canopies so that they open symmetrically. Such umbrellas are often adversely affected by strong wind which can blow their canopies inside out, and many inventions have been directed to improving such umbrellas to better withstand strong winds such as by providing vents in their fabric covering or by providing pole structures which can allow wind to pass therethrough in various ways. Some umbrellas are spring-loaded, that is, their concave structures are movable when sufficient wind force is exerted thereon; and when such force is no longer present, the concave structures return to their normal position. One patio umbrella of the prior art spins on its central shaft when strong wind blows against it in order to dissipate the force of the wind. Despite the incorporation of such wind-resistant features, prior art hand-held canopy umbrellas are still adversely affected by strong winds which can turn their canopies inside-out.
Yet another negative of prior art umbrella structures is that their construction is labor-intensive because of their complicated construction utilizing many parts. Many times it is completely impractical to repair umbrellas because of the high cost of repairing their thin metal struts which can be bent by the force of high winds against the canopy. Thus, if damaged, such prior art umbrellas often must be thrown away.